In the Barents Sea commercial snow crab(Chionoecetes opilio)fishery,an increase in catch efficiency of the conical pots is important for the profitability of the industry.Light emitting diodes(LEDs)have previously bee...In the Barents Sea commercial snow crab(Chionoecetes opilio)fishery,an increase in catch efficiency of the conical pots is important for the profitability of the industry.Light emitting diodes(LEDs)have previously been tested for increasing catch efficiency of the snow crab pots.These earlier experiments have shown varying results ranging from large increase in snow crab catches to no significant effect.These experiments have used different pot soaking times;however,the soaking time might affect the impact of LEDs on catch efficiency.In commercial snow crab fishery,the pot soak time is varying which has not been considered in earlier experiments testing the effect of LEDs.Therefore,this study examined whether pot soaking time can explain the observed differences in relative catch efficiency of snow crab pots with and without LEDs with soak times ranging from 2 to 14 days in the Barents Sea snow crab fishery.For target sizes of snow crab(≥95 mm carapace width),results indicated an increase in catch efficiency between 10 and 30%for pots with LEDs with exception of one experiment using six days soak time.However,experimental results were subjected to large uncertainties and,except from one experiment with five days soak time,the estimated increases were nonsignificant.Furthermore,the pot soak time was not found to impact the effect of white LEDs on capture efficiency.展开更多
Gillnets are one of the most commonly used fishing gears in both marine and inland waters.Different colour filament nettings are often used in gillnets.However,the effect of gillnet colour on catch efficiency is uncle...Gillnets are one of the most commonly used fishing gears in both marine and inland waters.Different colour filament nettings are often used in gillnets.However,the effect of gillnet colour on catch efficiency is unclear for most fisheries.Therefore,in this study we investigated the effect of gillnet colour on the catch efficiency in pearlspot(Etroplus suratensis)fishery in Vembanad lake,India.Gillnet colours tested were transparent,green and blue.Results showed that in this fishery,the catch efficiency of gillnets of the three colours tested differed significantly.The highest catch efficiency of pearlspot was shown by green gillnets compared to transparent or blue netting.Specifically,green gillnets on average were estimated to be 74%more efficient compared to transparent gillnets.For the green compared to the blue gillnets,the catch efficiency was estimated to be higher by 81%.These results demonstrate that gillnet colour can be an important factor significantly affecting the catch efficiency of this fishing gear.展开更多
The use of light in pots has been shown to increase snow crab catch rates in eastern Canada and the Barents Sea,where better fishing efficiency could result in less fuel consumption,and financial and ecological benefi...The use of light in pots has been shown to increase snow crab catch rates in eastern Canada and the Barents Sea,where better fishing efficiency could result in less fuel consumption,and financial and ecological benefits.However,some light characteristics necessary for maximizing efficiency have yet to be researched.The purpose of this study was to determine if there is a change in catch per unit effort(CPUE;number of snow crab per pot)and size selectivity of snow crab with varying light intensity.Three types of experimental luminescent-netting pots were used,each type with a different level of light intensity via the amount of phosphorescent strands woven into the pot netting,(either 2-,4-,or 6-strands)and were compared to the traditional pot used in the fishery.There were mixed results among treatments,with the 2-strand pot catching fewer snow crab<103 mm carapace width(CW)and more snow crab≥103 mm CW than the traditional pots,but overall,had a lower CPUE for legal and sub-legal sized males(14.8 and 3.1 per pot,respectively)than the traditional(16.1 and 5.5 per pot,respectively)when considering all size classes.When compared to the traditional,the 4-strand pot caught more legal and sub-legal(CPUE of 18.8 and 8.0 per pot,respectively)snow crab in terms of CPUE but caught fewer commercial snow crabs from 95 to 98 and 103-113 mm CW.The brightest intensity pots(6-strand)showed no significant difference in CPUE or size selectivity in comparison to the traditional.Increased light intensity pots either had no effect on snow crab capture(6-strand)or produced unwanted results(loss of commercial sizes,increase in sub-legal sizes).Conversely,the 2-strand pot showed decreases in juvenile crab catch and increases in the catch of the most valuable size-classes observed,which are attractive results to fisheries managers and harvesters,respectively.These results,combined with a large price increase,suggest that higher light-intensity pots are not attractive for the commercial fishery.展开更多
基金grateful to the academic editor and reviewers for their valuable comments,which have improved our manuscript.This project was funded by the Norwegian Research Council(CRABTECH Ⅱ,grant number:296044).
文摘In the Barents Sea commercial snow crab(Chionoecetes opilio)fishery,an increase in catch efficiency of the conical pots is important for the profitability of the industry.Light emitting diodes(LEDs)have previously been tested for increasing catch efficiency of the snow crab pots.These earlier experiments have shown varying results ranging from large increase in snow crab catches to no significant effect.These experiments have used different pot soaking times;however,the soaking time might affect the impact of LEDs on catch efficiency.In commercial snow crab fishery,the pot soak time is varying which has not been considered in earlier experiments testing the effect of LEDs.Therefore,this study examined whether pot soaking time can explain the observed differences in relative catch efficiency of snow crab pots with and without LEDs with soak times ranging from 2 to 14 days in the Barents Sea snow crab fishery.For target sizes of snow crab(≥95 mm carapace width),results indicated an increase in catch efficiency between 10 and 30%for pots with LEDs with exception of one experiment using six days soak time.However,experimental results were subjected to large uncertainties and,except from one experiment with five days soak time,the estimated increases were nonsignificant.Furthermore,the pot soak time was not found to impact the effect of white LEDs on capture efficiency.
基金financed by the Research Council of Norway(grant number:310008).
文摘Gillnets are one of the most commonly used fishing gears in both marine and inland waters.Different colour filament nettings are often used in gillnets.However,the effect of gillnet colour on catch efficiency is unclear for most fisheries.Therefore,in this study we investigated the effect of gillnet colour on the catch efficiency in pearlspot(Etroplus suratensis)fishery in Vembanad lake,India.Gillnet colours tested were transparent,green and blue.Results showed that in this fishery,the catch efficiency of gillnets of the three colours tested differed significantly.The highest catch efficiency of pearlspot was shown by green gillnets compared to transparent or blue netting.Specifically,green gillnets on average were estimated to be 74%more efficient compared to transparent gillnets.For the green compared to the blue gillnets,the catch efficiency was estimated to be higher by 81%.These results demonstrate that gillnet colour can be an important factor significantly affecting the catch efficiency of this fishing gear.
基金funded by the Canadian Centre for Fisheries Innovation(CCFI),an Ocean Frontier Institute(OFI)Seed Fund,and the project SnowMap.
文摘The use of light in pots has been shown to increase snow crab catch rates in eastern Canada and the Barents Sea,where better fishing efficiency could result in less fuel consumption,and financial and ecological benefits.However,some light characteristics necessary for maximizing efficiency have yet to be researched.The purpose of this study was to determine if there is a change in catch per unit effort(CPUE;number of snow crab per pot)and size selectivity of snow crab with varying light intensity.Three types of experimental luminescent-netting pots were used,each type with a different level of light intensity via the amount of phosphorescent strands woven into the pot netting,(either 2-,4-,or 6-strands)and were compared to the traditional pot used in the fishery.There were mixed results among treatments,with the 2-strand pot catching fewer snow crab<103 mm carapace width(CW)and more snow crab≥103 mm CW than the traditional pots,but overall,had a lower CPUE for legal and sub-legal sized males(14.8 and 3.1 per pot,respectively)than the traditional(16.1 and 5.5 per pot,respectively)when considering all size classes.When compared to the traditional,the 4-strand pot caught more legal and sub-legal(CPUE of 18.8 and 8.0 per pot,respectively)snow crab in terms of CPUE but caught fewer commercial snow crabs from 95 to 98 and 103-113 mm CW.The brightest intensity pots(6-strand)showed no significant difference in CPUE or size selectivity in comparison to the traditional.Increased light intensity pots either had no effect on snow crab capture(6-strand)or produced unwanted results(loss of commercial sizes,increase in sub-legal sizes).Conversely,the 2-strand pot showed decreases in juvenile crab catch and increases in the catch of the most valuable size-classes observed,which are attractive results to fisheries managers and harvesters,respectively.These results,combined with a large price increase,suggest that higher light-intensity pots are not attractive for the commercial fishery.
